


Inner Workings

by CrystalMythic_xX



Category: Dorohedoro
Genre: Blood and Injury, Canon-Typical Violence, Fluff, Kasukabe being weird, Kasukabe is 64 yrs old in his 18 yr old body, Light Angst, M/M, Sexual Tension, Spoilers, Surgery, Takes place after all the events, Violent Research, You use magic, mentions of past love, mentions of polyamory
Language: English
Status: In-Progress
Published: 2021-01-18
Updated: 2021-01-21
Packaged: 2021-03-14 06:09:36
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 3
Words: 4,597
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28790760
Author URL: https://archiveofourown.org/users/CrystalMythic_xX/pseuds/CrystalMythic_xX
Summary: After the near genocide of all magic-users due to the rain, you decided to take a vacation to Hole. From there after a violent encounter, you meet a strange man who is a bit too happy to see the likes of you. There is a lot to learn in this chaotic world.
Relationships: Kasukabe | Haze/Reader
Kudos: 2





	1. The Beginning of Hole

**Author's Note:**

> Another warning: This takes place after the events of the manga.

How did this happen? You had your guard up too, until next thing you know your head was slammed into the floor. You were getting kicked everywhere before they grew bored and left you to bleed. "How unfortunate, I'll have to bring you back. Bear with me, alright?" A chirper voice asks as you feel yourself hoisted upwards. You look up slightly, only to see a huge roach run towards you- screeching. "Help me with her, will you-" your vision and hearing fades, unable to keep yourself conscious. You stirred in your sleep, hearing foggy voices within the darkness. You wake up in a run-down hospital room, feeling a nail being kicked into your head constantly. "Oh hey, you're awake. I'm Vaux." A bald man introduces himself, blowing smoke away from you. You move very slowly, looking around and then back at him. "I'm a magic user. You're not going to kill me?" You ask, taking caution for your life regardless. He merely shrugs, shaking his head then giving you a small smile. "I'm sure you would've tried to kill me if you were bad. Even then- I'd be able to defend myself from you guys... kinda." You roll your eyes but speak no further, taking in the small sentiment that your guard can be lowered for now. Vaux clears his throat before speaking," What brings you to Hole? Not to experiment on people, right? As much as I need the money, this establishment was made to help." You shake your head gently before informing him," I came here since there was rain in my world. I thought I'd take the chance to escape it but..." Looking away, you stare at the window as it continues to make _pitter-patter_ sounds of the rain landing on it. "Ahh, well... you tried, at least. Do you plan on going home anytime soon?" You shake your head again. "I came here to take a vacation. I have seen the feud between Hole and my world calm down a bit, so I wanted to spend some time here." A knock was heard before someone came in, revealing a young man with a huge lab coat, black shirt, a metallic wrist watch, and a cigarette in his mouth. "Feeling a bit under the weather, I assume?" he asks. "Quite literally. I shouldn't be here though, since I'm not exactly part of your general clientele-" Before you were able to get up from your bed, the doctor gently pushes you back onto the bed with his hand. "No worries here, I chose to treat you." You look at him with surprise- wondering what to say. He points to himself and grins proudly," I'm Haze Kasukabe, better known as Doctor Kasukabe. I help run the hospital but I mostly do independent research."

You sit up at the very least, relaxing your arms in front of you. "What kind of research do you do, Dr. Kasukabe?" He smiles, sitting backwards on a chair so he is keeping eye contact with you. "Oh- I research magic users! I'd love to learn more about them." The blood within you runs cold. _'Magic users? Not only do I get beaten to death, I am going to be researched on... My life was nice while it lasted I guess-'_ Kasukabe laughs, interrupting your train of thought. "Don't worry, I won't research on anyone who doesn't consent. This really was just me saving you out of concern." You sigh in relief but only for a moment. "I'm gonna check on the other patients. See ya." Vaux takes his leave, leaving only the two of you in the room. Kasukabe gets up and takes out a checkboard. "I'm going to run a simple diagnostic on you. Answer me as clearly as you can." With the click of his pen, he begins.

"Headache?"

"Yes."

"Blurry vision?

"Yes.

"Difficulty hearing?"

"A little bit."

"Hungry?"

Your stomach growls, making you think about food. Food is definitely different from your world, who knows what is in it from Hole? "....No." The doctor merely puts his clipboard away. He begins to gather your things before approaching the door. "Come on, let's get going. Just stay nearby." You nod, slowly shuffling off the bed and making your way behind him. You follow him closely within the halls of The Hospital, seeing the occasional room open. Every passing room had a few people who are victims of magic users. The both of you step outside, the roof only barely shielding you from the rain. Kasukabe opens up a large umbrella that is slightly transparent. "This will keep the rain off you for the most part. I'll make it worth your while, don't worry." He reassures you happily, making you a bit inclined to trust him. You walk right next to him to be shielded from the rain as much as possible, but held onto his arm for balance. You both trudge past many buildings and people- some of them greeted Kasukabe while on their merry way. Soon, you both approach a small establishment named "The Hungry Bug." He closes the umbrella while letting himself in, you hiding behind him a little bit. "Oh, Dr. Kasukabe! A box, yes?" A blonde girl comes out of the kitchen, looking a bit tired but she seems to be keeping up well. "Make that four, please. I brought a guest with me." You two make your way to a booth, sitting comfortably across each other. "Ah- I didn't get your name, by the way. What's your name?" Kasukabe asks as he crosses his arms on the table. "I'm (Y/N). I... mostly wanted to escape the rain." you answer bluntly. The blonde woman comes over to you two, sliding two boxes on the table. "Who is this, Kasukabe?" Before you could have answered her properly, you were already devouring a couple fresh gyozas! "He's (Y/N). I saw him getting beat up by some guys nearby The Hospital." The girl hums, looking at you almost intensely. "I come in peace..." You groan, eating more gyoza to make it apparent that you don't want to talk. She chuckles and pats the table. "I'm Nikaido, (Y/N). You can count on me for anything, alright? Anyone that knows Kasukabe is good in my book." She walks off, leaving you to finish the last of your gyozas. Glancing over the clock, you realize that it is getting dark- meaning you might not have a place to stay overnight. "You alright, (Y/N)? You look panicked." Kasukabe states. "I just don't have a place to stay. I'd shift to my room from my world, but I don't want to use my smoke while I'm at Hole." You answer. Kasukabe holds his chin, appearing to be thinking of something. "Why not stay with me? I can provide you a place to stay." He offers. You squint your eyes at him before asking, "What must I do in order to return the favor to you?" Kasukabe never fails to hold his smile, but it looks only slightly sinister than before. It could just be you. "I'd like to do research on you! I will warn you of some things before hand as well as ask you questions. That's fine, right?" You nod in response. "Alright, it's settled then!"

You say your goodbyes to Nikaido and follow Kasukabe closely behind. After some turns, you arrive to what looks like a Minka- a bit damp looking, but not ruined. Kasukabe opens the door, a weird fog of smoke drifting within the home. "Uhm... this is a bit.... scary." You comment. The doctor grabs a vacuum and turns it on, absorbing all the smoke swiftly. Every second that passes, you see the hallway brighten up without any entrances merging with one another. "Nothing to worry about. I clean often enough so it doesn't do anything permanent. Follow me, I'll show you around." He says. You both walked in silence, Kasukabe showing you rooms of where his kitchen is, the entrance, a small garden... "This is my magic user research, (Y/N). You don't have to see it if you don't want to." He comments, holding the door only slightly that ominous green light is spewing out. "It's fine. I'd like to know what makes you so intrigued to research since I'll be staying here for some time." You answer as Kasukabe opens the door of his lab. There are large tanks of magic users preserved in some liquid while on the side of a wall is a corkboard littered with various masks- likely from the deceased. You felt only slightly sick, but the sight of death is common to everyone. "I'm not going to end up like this... right?" You ask, tapping one of the tanks. "Of course not. These are magic users who experimented on people- I had some cleaners of my own to bring them to me." He says, walking out of the room and down the hall before walking into another room. The room was spacious, the tatami was neat and there was a futon already out. "You can sleep here from now on, (Y/N). I'll be in the lab if you need anything. Ciao." Kasukabe waves goodbye, leaving you on your own in the room. You look outside of the sliding doors, seeing the light sprinkle of rain. This gig might not be so bad.


	2. First Look

**Summary for the Chapter:**

> Something already harsh, but at least Kasukabe is honest about it.

**Notes for the Chapter:**

> Warning: Surgery.

You wake up slowly, stretching your arms to wake up your muscles. Looking around, everything is the same except the outside is its usual bleak daytime. While taking a deep breath in, you smell something delicious being made. Getting your socks on, you walk down the hall towards the kitchen, seeing Kasukabe plating meat, veggies, and rice onto separate plates. "Good morning, (Y/N)! I made breakfast for us." He says, sitting himself down at the kotatsu. You sit across of him, noticing his meal is much lighter than yours. "I appreciate the breakfast, Dr. Kasukabe but.... why do I have so much?" You ask, chowing down on your plate. Kasukabe smiles after swallowing his food," You are going to go through your first trial today! I've considered doing the most difficult ones first so you won't have to do them for a long time. You're going to need all the energy for it." He warns. You feel a pit in your stomach, but you could only trust that he does not intend to kill you. "Well, I'll take the honesty. What is it that you need from me today?" You drink a glass of orange juice, feeling the cold liquid run down your throat. "I'll be dissecting you while you are awake! It will help me understand magic user anatomy better as well as see if there are differences in magic skill." He informs, making you nearly choke on your food. "D-dissect? Awake? I'm going to feel all this!?" You blurt out while hugging your arms due to the sudden chill. "To an extent. I have a couple tools to make this operation as safe as it can be. If it helps you, you'll be my second living subject." He reassures playfully, causing you to shiver from fear. "I may need my health insurance for this-" "Nope."

You lay on at a large medical bed, your left arm sticking onto an extra platform while your right relaxes on your stomach. "How are you feeling right now, (Y/N)?" Kasukabe asks, putting on blue latex gloves and assembling a couple tools on a tray. "Nervous. Mildly terrified. I had my odd experience with other magic, but not so much with surgery." You can feel your heart pounding while you try to calm yourself down. Kasukabe places the tray nearby you, causing the tray to clatter lightly but enough to grab your attention. Your eyes focus on one thing on the tray; the two black bottles of smoke with names on them. "Is that smoke? I'm not gonna get smoke injected in me, right?" You ask in a slightly panicked state. Kasukabe puts on his mask and a pair of glasses that have a light attached on them. "None of that will happen. The smoke will help this operation go as smoothly as possible. You can thank Shin and Noi for that." You flicker at the names, recalling who they are. "Oh? I didn't know some of En's family associated with people in Hole. Power really does have roots all over." You comment. The brunette hums in agreement before patting some kind of numbing medicine on your arm. "Tell me if it is too much so I'll cease operating." He warns, you nodding in response. He opens the Shin bottle, spreading it on your arm- causing it to be chopped like meat! Your arms are segmented in even parts from shoulder to your fingers, the inside being visible but intact so there is no bleeding. The pain is apparent, but not excruciating- you still feel your arm but oddly it is only twitching. Kasukabe quickly separates the parts of your arm farther from each piece.

"How does it feel right now? Nothing too bad, right?" Kasukabe asks, flicking his light on. "Nothing too painful. I can feel my arm but I can't quite move it as easily as my right arm. I could possibly move parts of it if I tried hard enough." After informing Kasukabe, he nods and grabs a metal rod that is slightly dented at the tip. He begins to gently prod a segment of your arm, making you resist the urge to squirm. He hums a quiet tune, working back and forth from your arm to his clipboard. "How aware are you when it comes to the location of your smoke veins?" He asks, continuously prodding one spot. "Mildly aware. My magic output is strong so I can feel its flow when I have to work up a sweat." Kasukabe nods, writing quickly on his clipboard before turning back to your arm. A looming silence fills the room, you looking at the corner while he closely observes your limb. After a while, Kasukabe flicks his light off and looks at you. "Anything on your mind, (Y/N)?" You look at your arm and back at him, trying to think of something to say. "In a weird way, my arm looks like a pork katsu." You almost immediately regret your words until Kasukabe laughs at your morbid joke. "You're right- it does look like one. I could treat you to some after this if you'd like." He offers, but you politely decline. "I'd like to just relax after this, it isn't everyday I become minced meat." You earn another chuckle from the doctor, making your ego inflate a little bit for being a comedian. Kasukabe opens the Noi bottle, making the smoke envelope your arm. Quickly as if it is like wax melting together, your arms reconnect perfectly. Kasukabe moves away with the tray, cleaning his tools and leaving you at the medical bed. You slowly lift up your arm, flexing it and observing if there are any openings possibly left behind. "Take it easy with that arm, (Y/N). It is healed right now but it will take some time for it to be fully operational." He says. "Alright, I'll be walking around then! Call me if you need anything." You say as you hop off the bed, holding your left arm gently.

Walking around the house was pleasant, even if it was in Hole. You can tell that Kasukabe really cares for spring cleaning, that or life is much easier when the halls and rooms aren't warped with one another. Taking much time to relax and admire the home you realize; you really have nothing to do. Deciding a good way to spend your time, you make your way to Kasukabe's lab, seeing the door slightly opened. You peek in as quietly as possible, seeing Kasukabe rubbing his forehead of sweat. His labcoat was rested on the office chair, leaving him wearing a plain black shirt while revealing the hidden tattoos on his arms. Taking a closer look at his desk, you see a detailed sketch but can't quite make out what it really is. You gently knock on the door to announce your presence, seeing the other male turn towards the door to see you. "Come on in, (Y/N)." Walking in the lab once again, you lean in to the desk from behind him for a better look at the sketch. "Is this my arm, Kasukabe?" You ask, admiring the attention to detail. He really has the anatomy of your arm down to every fiber. "In a way, yes. I want to keep a record of magic user anatomy since it is about time to keep track of history." He says, rolling up the sketch, putting his coat on and storing it in a pocket. "Would you like to accompany me? I'm going to send this in to be sculpted, unless you'd prefer to be in the house." You look around, then shrugging as there is nothing else to be done in the house anyway. Both of you get your shoes on and begin to walk. The deeper you two got into the city, the denser the buildings were. Everything seems to be forcefully packed as well as the people becoming visibly intimidating. "Not to be judgmental or anything but.... I'm not liking the look of these parts." You say- and as if on cue, a couple of people stand in your way. Kasukabe gently moves you behind him with his arm," Behind me."

The ambushers begin to close in, knives flashed out. Kasukabe takes out a remote and presses a button, sending a signal to devil-knows-what. "You think that dud will save you? It hardly did anything!" One of them say, charging towards you two! The floor begins to vibrate, all of it leading to the manhole! "Shocking!" A man-sized roach with red sneakers bursts out of the manhole, landing in front of the robbers. "W-what the hell is that!?" The roach charges into the assailants, aggressively pounding them into the wall. "Thanks, Jonson! Keep them occupied for us." Kasukabe grabs your hand before bolting into a three-way alley, hiding you both into one of them. You're desperately catching your breath in his chest, feeling his heartbeat. Footsteps echo within the alleyway, running past you too as well as Jonson's screaming. "Alright... I think we're good now, (Y/N)." The brunette says, looking down at you on his chest. You look up and realize the closeness, immediately pulling back while uttering several apologies. "Let's get moving. We're at the building." You follow the male inside, seeing a plethora of body parts that seem almost real- the smell of the lobby only convincing you more. Kasukabe tells you to wait in the lobby while he walks behind a curtain, leaving you alone. Looking around, you see a corpse sitting across from you. Despite efforts to look away, it always seemed to move from the corner of your eye. You felt like you weren't alone in the lobby. "Let's head back, (Y/N). We got what we needed!" Kasukabe comes out with a disembodied arm that has dotted segments printed on the flesh. You two exit the building, walking all the way home without a hitch. Kasukabe displays the arm on his lab desk, inspecting it before placing his hands at his hips in triumph. "Good work today, (Y/N). Any cravings for dinner?" He asks. "I think I'd like to have the pork katsu."

**Notes for the Chapter:**

> Why? Why so much effort for something and someone so niche? Well... it's because I am probably the only one who likes Kasukabe a lot.


	3. Unexpectations

**Summary for the Chapter:**

> You learn more about the doctor himself during a hot day.

**Notes for the Chapter:**

> Manga Spoilers

Various trials have been moderated from light to extreme, though there is nothing you couldn't handle. Despite the professionalism Dr. Kasukabe maintains, what goes on in his mind? He is clearly not to be taken lightly if anyone is fooled by his appearance, he has his unorthodox ways of survival. Regardless, he has a heart. "I knew Hole has rain, but I didn't think it would have this blasted heat..." You groan, fanning yourself with your shirt. "Really? You have to tell me the weather at your world one day." Kasukabe sounds out of breath despite the both of you barely moving. It is for the best, since the only fan in the house is the one you both are sharing. Both of you laid in front of the small fan rotating between you two, avoiding as much sunlight as possible. You look over at your housemate, seeing him remove his coat and toss it in a corner. "Hm? Aren't you a bit too young for tattoos? Unless you're part of some kind of gang-" Kasukabe shakes his head, looking over at his arms. "Ah, about me. Well, I'm actually sixty-four!" You feel shock, but recover quickly. "Ahh, that explains a lot actually." Kasukabe nods before he continues. "I got these around eighteen while I was studying in the medical field. I've been researching magic users all my life, so this rejuvenation spell really helps! Oh- and this too." The brunette crawls to a drawer before coming back, handing you a book with a devil sign on the cover. You look through it, seeing various magic users ranging from pitiful to powerful- a couple of them matching the tattoos on his arms. "To anyone else, it would seem you almost want to be a magic user yourself. I admire your dedication to studying us though. Our... erm... devils... certainly aren't keeping track." You whisper the last part, as hope that no devil would consider your comment as blasphemy.

You hand the book back to the scientist before laying back down, staring up at the ceiling. "Did you know that I'm married to a devil?" He says. You slowly turn around and bow to Kasukabe, hands flat on the floor. "I apologize for my words of blasphemy, please don't throw me into hell early." Earning a laugh from Kasukabe, you presume that it likely isn't as serious as you think it is. "I mean-! I was, but it is a past that I cherish." You hold your tongue, seeing the researcher's face falter only a bit. He solemnly stares at his ring before looking up at you. "What about you, ever been in love?" You shake your head, perching your head on your hand as you lay down. "What was your wife like, old man?" Kasukabe relaxes while leaning on his arm, his short hair dripping the occasional sweat. "She arrived in Hole similar to how you did, (Y/N). Down on her luck, so I helped her out. She stayed with me since then before leaving Hole all of a sudden. I didn't take any offense to it, but it was meaningful. We're on good terms!" He gets up and stretches, wiping the sweat off his forehead. "Remind me not to get you mad then. What is your wife's name, by the way?" You ask, thinking of all the devils you know in your head From what you knew so far, there was only very few that could possibly be the one. Kasukabe offers you a hand, which you accept as he pulls you up from the floor. "Haru is her name! She says she is a famous singer in Hell." You only nod, keeping her in mind in case you find yourself in trouble with the devils. Kasukabe starts walking out, signaling you to follow him with the wave of his hand. Kasukabe takes you to the garden, suddenly disappearing behind a bush. "...Eh? Kasukabe? Where did you go-" You suddenly feel nearly scalding water on your back! "Oh- my bad." "WHY DIDN'T YOU CHECK, ARE YOU TRYING TO MELT ME!?" You screech, releasing smoke from your fingers towards your back. You cool your back off as quickly as possible, sighing in relief. "Ooh, temperature. That type of magic is relatively rare, isn't it?" He asks. "After the rain in my world? Maybe even more so. I've only use it for menial tasks since Blue Night Festival can really leave targets on someone for a long time."

Kasukabe turns the nob of the hose, making the water release as a cold mist. You both sit on the shaded porch, Kasukabe blowing mist between you two. "What is the weather like at your place, (Y/N)?" He asks, looking upwards at the sky. "Always fine. It hardly ever gets cloudy but it can get hot if something happened. Otherwise, people can wear anything without worry." You look at your drenched shirt before removing it, pointlessly wringing the water out into the ground. "Hm, that explains the clothes I've seen magicians wear- sometimes their clothes barely hide anything!" Kasukabe mocks one, lifting his shirt to the middle of his chest. "Arguably true. Magic has a higher value than skin most of the time." Before you could continue on, you see a huge shadow block your vision. "Shocking!" Jonson shouts, waving his arms in the air. He reeks of blood and sewage, clearly stained everywhere. "Hey Jonson. Those people are gone now, right?" Kasukabe asks, earning a nod from the mutated roach. You open a hand to ask for the hose before receiving it and pointing it towards Jonson. "I appreciate the effort, Jonson- but please bathe every once in a while." You comment. Eventually, you and Kasukabe began to wash Jonson in a small tub outside like he is a dog. Jonson seems to be enjoying it due to the occasional sighing and twitch of his antennas. "You're a good boy, Jonson. I'm proud of you." Kasukabe coos, petting the roach on his head every now and then after a good scrub. After much time, you both back up and look over Jonson- a clean roach that did no crime in a lawless world. "Shocking!" Jonson cheers before hopping into the back house, disappearing. "Hopefully he doesn't get dirty again..." You mutter before sitting back down. "Even so, that was still fun." Kasukabe pops a cigarette into his mouth before flicking a lighter. "Smoking in the heat? Isn't that counter-productive?" You ask. "Yeah, but it helps in its own way. We've been making great progress. You've been a lot of help!" He smiles, making you unable to resist smiling back at him and nodding in agreement.

Night falls, though the heat has only barely settled. You look up at the ceiling, unable to fall asleep. You get up quietly to make your way to Kasukabe's room, knocking gently. There is light pattering of footsteps approaching the door, revealing the scientist who seems to still be fully awake. "You too, (Y/N)?" He asks. "Yeah. I didn't really want to be selfish using my magic while living with you so I thought I'd come by- if that's alright with you." Getting a nod of approval, you enter the room and set up a futon next to his. "I'm gonna need you to lift up your shirt and show your back to me. I'll leave a thin layer so it can cool you off for the night." You inform him, seeing him doing what you told him. Looking over at his back in the moonlight, you see trails of scars. Shaking it out of your head, you apply the thin layer of smoke before patting him on the back so he can put his shirt back down. "Thanks for the free cooling pad, (Y/N)." He shakes your shoulder lazily as a show of gratitude before settling into his bed. "No problem, it's the least I could do. Goodnight, Kasukabe." "Sleep well, (Y/N)."

**Notes for the Chapter:**

> It is currently 1am at this point in time. I inhaled helium from a balloon. It was horrible.


End file.
